1. Field of the Invention
The present invention relates to a printed circuit board. More particularly, the present invention relates to a printed circuit board structure, which facilitates tracing back and identifying the production information of each finished printed circuit board quickly and effectively.
2. Description of the Prior Art
As known by persons of ordinary skill in the art, the manufacturing process of printed circuit boards (PCBs) usually starts with a bulk of substrate as a starting material. First the inner-layer connect is produced to form the necessary layout, which includes pre-treatment, photo-resist application, exposure, development, etching and removal of the photo-resist, then the surface of copper is roughened to increase the adhesion to the insulation resins. Afterwards, they are laminated with plastic sheets. The electric conductivity is accomplished through holes by mechanic or laser means. The inter-substrate electric conductivity is accomplished by electroplating method. After the above steps the outer layer of the circuit boards is applied with a solder-resist to avoid short circuits when solder overflows during soldering and to work as a barrier to prevent the vapor and oxygen in the air from penetrating.
After the solder-resist is applied, a serial number or any necessary production information is formed on a pre-determined location of the substrate by printing or laser. Last, the substrate is diced to obtain multiple final PCBs and an electronic test is carried out on each PCB.
However, the current problem is that after the substrate is diced to multiple final PCBs, each final PCB does not possess a corresponding number such as lot number and panel number. In such a way, it is almost impossible to trace back flawed PCBs regarding the production lines, batch numbers and racks.
Accordingly, it is necessary to provide a low-cost method which is compatible with current process to effectively identify the production information such as panel number of each finished printed circuit board produced by multiple factories and different production lines/batch lines after dicing and to identify the flawed PCBs regarding the batch lines and the rack and to perform the root cause analysis.